WASHINGTON — Moments before Sen. Larry Craig held a news conference to declare "I am not gay," Senate Republican leaders Tuesday requested an Ethics Committee investigation into the Idaho Republican's arrest in a public restroom.

The unusual move underscored the political difficulties facing Craig, who pleaded guilty earlier this month to a disorderly conduct charge and now says he regrets it. The senator was arrested at Minneapolis-St. Paul International Airport by a plainclothes officer investigating reports of "sexual activity in the public restroom," the police report said.

"This is a serious matter," said a statement issued by Senate Minority Leader Mitch McConnell, R-Ky., and his four top deputies. "Leadership is examining other aspects of the case to determine if additional action is required." Idaho Republican Party Chairman Kirk Sullivan urged Idahoans to "avoid rushing to judgment," but Republican presidential candidate Mitt Romney condemned Craig's actions as "disgusting."

In Boise, Craig refused to say whether he would seek re-election for a fourth Senate term next year. With his wife, Suzanne, by his side, Craig insisted that his decision to plead guilty was an "overreaction." He blamed the Idaho Statesman, saying he was stressed because of the paper's investigation of his sex life.

The newspaper reported Tuesday that it interviewed one man who claimed to have had a sexual encounter with Craig at a train station bathroom a few blocks from the U.S. Capitol, and two others who said they had been sexually propositioned by Craig. None of the men was identified. The newspaper reported that Craig denied their charges in an interview one month before his June 11 arrest in Minneapolis.

Craig, 62, said he had been "relentlessly and viciously harassed" by the Statesman, which withheld its report until after news of the senator's guilty plea broke.

In a statement posted on the Statesman's website, Managing Editor Bill Manny said: "We worked hard and behaved responsibly, not publishing a story until it was ready. … Our story outlined what we've done and it speaks for itself."

The senator said he pleaded guilty to the disorderly conduct charge "in hopes of making it go away."

"I did nothing wrong at the Minneapolis airport," Craig said. He took no questions from reporters.

According to an account of the arrest released Tuesday by Minneapolis airport police, Craig was arrested after peering into a bathroom stall occupied by the plainclothes officer and then touching the officer's foot with his own and waving his hand from under the neighboring stall.

On June 22, Craig "appeared agitated" when he returned to the police operations center at the Minneapolis airport, according to a report filed by an officer who spoke with him, Adam Snedker. The senator said he needed contact information "so his lawyer can speak to someone," Snedker's report said. At his news conference, Craig said he did not retain counsel until this week.

The senator pleaded guilty in a Hennepin County court Aug. 8, paid $575 in fines and was put on probation for a year, according to a docket obtained by the Associated Press.

Romney, who had counted Craig as one of his key supporters, called the senator's actions "very disappointing," on CNBC. "I'm sorry that he's fallen short," Romney said. "Frankly, it's disgusting."

Craig "owes the people of Idaho a more credible explanation than what he has provided," Patrick Sammon, president of the Log Cabin Republicans, an organization of gay party members, said in a statement. "Innocent people don't plead guilty."

Craig's is one of 21 Senate seats that Republicans will try to defend next year as voters disenchanted with President Bush and the Iraq war head to the polls. The heavily Republican state normally would not be competitive but if Craig tries to seek re-election "it could get interesting real quickly," said Stu Rothenberg, a non-partisan analyst who follows congressional races.

Larry LaRocco, a former Democratic congressman who is running for the Idaho Senate seat, refused to comment on Craig's difficulties. "There are a lot of vulnerabilities regardless of what happened," he said.

Craig served six years in the Idaho Senate and 10 in the U.S. House before entering the Senate in 1991. He has voted to ban gay marriage and has opposed expanding the definition of hate crimes to include attacks on gay people.